scholarly journals Cardiac ryanodine receptor distribution is dynamic and changed by auxiliary proteins and post-translational modification

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Parisa Asghari ◽  
David RL Scriven ◽  
Myles Ng ◽  
Pankaj Panwar ◽  
Keng C Chou ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Ventricular Myocytes ◽  
Electron Tomography ◽  
Wistar Rat ◽  
Confocal Imaging ◽  
Post Translational Modification ◽  
Functional Changes ◽  
Cellular Environment ◽  
And Function ◽  
Correlation Microscopy

The effects of the immunophilins, FKBP12 and FKBP12.6, and phosphorylation on type II ryanodine receptor (RyR2) arrangement and function were examined using correlation microscopy (line scan confocal imaging of Ca2+ sparks and dual-tilt electron tomography) and dSTORM imaging of permeabilized Wistar rat ventricular myocytes. Saturating concentrations (10 µmol/L) of either FKBP12 or 12.6 significantly reduced the frequency, spread, amplitude and Ca2+ spark mass relative to control, while the tomograms revealed both proteins shifted the tetramers into a largely side-by-side configuration. Phosphorylation of immunophilin-saturated RyR2 resulted in structural and functional changes largely comparable to phosphorylation alone. dSTORM images of myocyte surfaces demonstrated that both FKBP12 and 12.6 significantly reduced RyR2 cluster sizes, while phosphorylation, even of immunophilin-saturated RyR2, increased them. We conclude that both RyR2 cluster size and the arrangement of tetramers within clusters is dynamic and respond to changes in the cellular environment. Further, these changes affect Ca2+ spark formation.

Ryanodine receptor as insecticide target

2021 ◽  
Vol 27 ◽  
Author(s):  
Arthur Samurkas ◽  
Li Yao ◽  
Hadiatullah Hadiatullah ◽  
Ruifang Ma ◽  
Yunxun Xie ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Review Paper ◽  
Agricultural Pests ◽  
Target Species ◽  
Resistance Mutations ◽  
Functional Changes ◽  
Wide Range ◽  
Low Toxicity ◽  
And Function ◽  
New Generation

: Ryanodine receptor (RyR) is one of the primary targets of commercial insecticides. The diamide insecticide family, including flubendiamide, chlorantraniliprole, cyantraniliprole, etc, targets insect RyRs and can be used to control a wide range of destructive agricultural pests. The diamide insecticides are highly selective against lepidopteran and coleopteran pests with relatively low toxicity for non-target species, such as mammals, fishes, and beneficial insects. However, recently mutations identified on insect RyRs have emerged and caused resistance in several major agricultural pests throughout different continents. This review paper summarizes the recent findings on structure and function of insect RyRs as insecticide target. Specifically, we examine the structures of RyRs from target and non-target species, which reveals the molecular basis for insecticide action and selectivity. We also examine the structural and functional changes of RyR caused by the resistance mutations. Finally, we examine the progress in RyR structure-based insecticide design, and discuss how this might help the development of new generation of green insecticides.

scholarly journals Distribution and Function of Cardiac Ryanodine Receptor Clusters in Live Ventricular Myocytes

2015 ◽  
Vol 290 (33) ◽  
pp. 20477-20487 ◽  
Author(s):  
Florian Hiess ◽  
Alexander Vallmitjana ◽  
Ruiwu Wang ◽  
Hongqiang Cheng ◽  
Henk E. D. J. ter Keurs ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Ventricular Myocytes ◽  
Receptor Clusters ◽  
And Function ◽  
Cardiac Ryanodine Receptor

scholarly journals Peptide ligands of the cardiac ryanodine receptor as super-resolution imaging probes

2020 ◽  
Author(s):  
Thomas M. D. Sheard ◽  
Luke Howlett ◽  
Hannah Kirton ◽  
Zhaokang Yang ◽  
Georgina Gurrola ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Ryanodine Receptor ◽  
Peptide Binding ◽  
Super Resolution ◽  
Fluorescent Imaging ◽  
Confocal Imaging ◽  
Structural Basis ◽  
Functional Changes ◽  
Imaging Probes ◽  
Resolution Imaging

AbstractTo study the structural basis of pathological remodelling and altered calcium channel functional states in the heart, we sought to re-purpose high-affinity ligands of the cardiac calcium channel, the ryanodine receptor (RyR2), into super-resolution imaging probes. Imperacalcin (IpCa), a scorpion toxin peptide which induces channel sub-conduction states, and DPc10, a synthetic peptide corresponding to a sequence of the RyR2, which replicates arrhythmogenic CPVT functional changes, were used in fluorescent imaging experiments.Isolated adult rat ventricular cardiomyocytes were saponin-permeabilised and incubated with each peptide. IpCa-A546 became sequestered into the mitochondria. This was prevented by treatment of the permeabilised cells with the ionophore FCCP, revealing a striated staining pattern in confocal imaging which had weak colocalisation with RyR2 clusters. Poor specificity (as an RyR2 imaging probe) was confirmed at higher resolution with expansion microscopy (proExM) (~70 nm).DPc10-FITC labelled a striated pattern, which had moderate colocalisation with RyR2 cluster labelling in confocal and proExM. There was also widespread non-target labelling of the Z-discs, intercalated discs, and nuclei, which was unaffected by incubation times or 10 mM caffeine. The inactive peptide mut-DPc10-FITC (which causes no functional effects) displayed a similar labelling pattern.Significant labelling of structures unrelated to RyR2 by both peptide conjugates makes their use as highly specific imaging probes of RyR2 in living isolated cardiomyocytes highly challenging.We investigated the native DPc10 sequence within the RyR2 structure to understand the domain interactions and proposed mechanism of peptide binding. The native DPc10 sequence does not directly interact with another domain, and but is downstream of one such domain interface. The rabbit Arg2475 (equivalent to human Arg2474, mutated in CPVT) in the native sequence is the most accessible portion and most likely location for peptide disturbance, suggesting FITC placement does not impact peptide binding.

scholarly journals Blocked O-GlcNAc cycling alters mitochondrial morphology, function, and mass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elizabeth O. Akinbiyi ◽  
Lara K. Abramowitz ◽  
Brianna L. Bauer ◽  
Maria S. K. Stoll ◽  
Charles L. Hoppel ◽  
...  
Keyword(s):  
Cellular Localization ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Morphology ◽  
Post Translational Modification ◽  
Mitochondrial Content ◽  
Protein Levels ◽  
Cellular Environment ◽  
And Function ◽  
The Impact

AbstractO-GlcNAcylation is a prevalent form of glycosylation that regulates proteins within the cytosol, nucleus, and mitochondria. The O-GlcNAc modification can affect protein cellular localization, function, and signaling interactions. The specific impact of O-GlcNAcylation on mitochondrial morphology and function has been elusive. In this manuscript, the role of O-GlcNAcylation on mitochondrial fission, oxidative phosphorylation (Oxphos), and the activity of electron transport chain (ETC) complexes were evaluated. In a cellular environment with hyper O-GlcNAcylation due to the deletion of O-GlcNAcase (OGA), mitochondria showed a dramatic reduction in size and a corresponding increase in number and total mitochondrial mass. Because of the increased mitochondrial content, OGA knockout cells exhibited comparable coupled mitochondrial Oxphos and ATP levels when compared to WT cells. However, we observed reduced protein levels for complex I and II when comparing normalized mitochondrial content and reduced linked activity for complexes I and III when examining individual ETC complex activities. In assessing mitochondrial fission, we observed increased amounts of O-GlcNAcylated dynamin-related protein 1 (Drp1) in cells genetically null for OGA and in glioblastoma cells. Individual regions of Drp1 were evaluated for O-GlcNAc modifications, and we found that this post-translational modification (PTM) was not limited to the previously characterized residues in the variable domain (VD). Additional modification sites are predicted in the GTPase domain, which may influence enzyme activity. Collectively, these results highlight the impact of O-GlcNAcylation on mitochondrial dynamics and ETC function and mimic the changes that may occur during glucose toxicity from hyperglycemia.

scholarly journals In situ structural analysis of Golgi intracisternal protein arrays

2015 ◽  
Vol 112 (36) ◽  
pp. 11264-11269 ◽  
Author(s):  
Benjamin D. Engel ◽  
Miroslava Schaffer ◽  
Sahradha Albert ◽  
Shoh Asano ◽  
Jürgen M. Plitzko ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Electron Tomography ◽  
Ion Beam ◽  
Asymmetric Membrane ◽  
Protein Arrays ◽  
Cellular Environment ◽  
Filament Bundles ◽  
Subtomogram Averaging ◽  
And Function

We acquired molecular-resolution structures of the Golgi within its native cellular environment. Vitreous Chlamydomonas cells were thinned by cryo-focused ion beam milling and then visualized by cryo-electron tomography. These tomograms revealed structures within the Golgi cisternae that have not been seen before. Narrow trans-Golgi lumina were spanned by asymmetric membrane-associated protein arrays that had ∼6-nm lateral periodicity. Subtomogram averaging showed that the arrays may determine the narrow central spacing of the trans-Golgi cisternae through zipper-like interactions, thereby forcing cargo to the trans-Golgi periphery. Additionally, we observed dense granular aggregates within cisternae and intracisternal filament bundles associated with trans-Golgi buds. These native in situ structures provide new molecular insights into Golgi architecture and function.

scholarly journals Right Heart Structure, Geometry and Function Assessed by Echocardiography in 6-Year-Old Children Born Extremely Preterm—A Population-Based Cohort Study

2020 ◽  
Vol 10 (1) ◽  
pp. 122
Author(s):  
Lilly-Ann Mohlkert ◽  
Jenny Hallberg ◽  
Olof Broberg ◽  
Gunnar Sjöberg ◽  
Annika Rydberg ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Ductus Arteriosus ◽  
Population Based ◽  
Right Heart ◽  
Functional Changes ◽  
Cardiac Phenotype ◽  
Extremely Preterm ◽  
Healthy Control ◽  
The Right ◽  
And Function

Preterm birth has been associated with altered cardiac phenotype in adults. Our aim was to test the hypothesis that children surviving extremely preterm birth have important structural or functional changes of the right heart or pulmonary circulation. We also examined relations between birth size, gestational age, neonatal diagnoses of bronchopulmonary dysplasia (BPD) and patent ductus arteriosus (PDA) with cardiac outcomes. We assessed a population-based cohort of children born in Sweden before 27 weeks of gestation with echocardiography at 6.5 years of age (n = 176). Each preterm child was matched to a healthy control child born at term. Children born preterm had significantly smaller right atria, right ventricles with smaller widths, higher relative wall thickness and higher estimated pulmonary vascular resistance (PVR) than controls. In preterm children, PVR and right ventricular myocardial performance index (RVmpi’) were significantly higher in those with a PDA as neonates than in those without PDA, but no such associations were found with BPD. In conclusion, children born extremely preterm exhibit higher estimated PVR, altered right heart structure and function compared with children born at term.

scholarly journals Membrane-associated phase separation: organization and function emerge from a two-dimensional milieu

2021 ◽  
Author(s):  
Jonathon A Ditlev
Keyword(s):  
Phase Separation ◽  
Cell Biology ◽  
Cellular Environment ◽  
Condensate Formation ◽  
Associated Proteins ◽  
Available Technology ◽  
And Function ◽  
Surrounding Membrane

Abstract Liquid‒liquid phase separation (LLPS) of biomolecules has emerged as an important mechanism that contributes to cellular organization. Phase separated biomolecular condensates, or membrane-less organelles, are compartments composed of specific biomolecules without a surrounding membrane in the nucleus and cytoplasm. LLPS also occurs at membranes, where both lipids and membrane-associated proteins can de-mix to form phase separated compartments. Investigation of these membrane-associated condensates using in vitro biochemical reconstitution and cell biology has provided key insights into the role of phase separation in membrane domain formation and function. However, these studies have generally been limited by available technology to study LLPS on model membranes and the complex cellular environment that regulates condensate formation, composition, and function. Here, I briefly review our current understanding of membrane-associated condensates, establish why LLPS can be advantageous for certain membrane-associated condensates, and offer a perspective for how these condensates may be studied in the future.

scholarly journals Sumoylation regulates the assembly and activity of the SMN complex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Giulietta M. Riboldi ◽  
Irene Faravelli ◽  
Takaaki Kuwajima ◽  
Nicolas Delestrée ◽  
Georgia Dermentzaki ◽  
...  
Keyword(s):  
Survival Rate ◽  
Muscular Atrophy ◽  
Motor Deficits ◽  
Cellular Distribution ◽  
Post Translational Modification ◽  
Smn Complex ◽  
Sensory Motor ◽  
Motor Neuron Loss ◽  
And Function ◽  
Small Nuclear Ribonucleoproteins

AbstractSMN is a ubiquitously expressed protein and is essential for life. SMN deficiency causes the neurodegenerative disease spinal muscular atrophy (SMA), the leading genetic cause of infant mortality. SMN interacts with itself and other proteins to form a complex that functions in the assembly of ribonucleoproteins. SMN is modified by SUMO (Small Ubiquitin-like Modifier), but whether sumoylation is required for the functions of SMN that are relevant to SMA pathogenesis is not known. Here, we show that inactivation of a SUMO-interacting motif (SIM) alters SMN sub-cellular distribution, the integrity of its complex, and its function in small nuclear ribonucleoproteins biogenesis. Expression of a SIM-inactivated mutant of SMN in a mouse model of SMA slightly extends survival rate with limited and transient correction of motor deficits. Remarkably, although SIM-inactivated SMN attenuates motor neuron loss and improves neuromuscular junction synapses, it fails to prevent the loss of sensory-motor synapses. These findings suggest that sumoylation is important for proper assembly and function of the SMN complex and that loss of this post-translational modification impairs the ability of SMN to correct selective deficits in the sensory-motor circuit of SMA mice.

scholarly journals Evidence for rapid structural and functional changes of the melanophore microtubule-organizing center upon pigment movements

1979 ◽  
Vol 83 (3) ◽  
pp. 623-632 ◽  
Author(s):  
M Schliwa ◽  
U Euteneuer ◽  
W Herzog ◽  
K Weber
Keyword(s):  
Complete Removal ◽  
Cell System ◽  
The State ◽  
Microtubule Assembly ◽  
Microtubule Organizing Center ◽  
Functional Changes ◽  
Organizing Center ◽  
Pigment Distribution ◽  
And Function ◽  
In Cells

Melanophores of the angelfish, pterophyllum scalare, have previously been shown to display approximately 2,400 microtubules in cells wih pigment dispersed; these microtubules radiate from a presumptive organizing center, the central apparatus (CA), and their number is reduced to approximately 1,000 in the state with aggregated pigment (M. Schliwa and U. Euteneuer, 1978, J. Supramol. Struct. 8:177-190). In an attempt to elucidate the factors controlling this rapid reorganization of the microtubule apparatus, structure and function of the CA have been investigated under different physiological conditions. As a function of the state of pigment distribution, melanophores differ markedly with respect to CA organization. A complex of dense amorphous aggregates and associated fuzzy material, several micrometers in diameter, surrounds the centrioles in cells with pigment dispersed, and numerous microtubules emanate from this complex in a radial fashion. In the aggregated state, on the other hand, few microtubules are observed in the pericentiolar region, and the amount of fibrous material is greatly reduced. These changes in CA morphology as a function of the state of pigment distribution are associated with a marked difference in its capacity to initiatiate the assembly of microtubules from exogenous pure porcine brain tubulin in lysed cell preparations. After complete removal of preexisting microtubules, cells lysed in the dispersed state into a solution of 1-2 mg/ml pure tubulin have numerous microtubules associated with the CA in radial fashion, while cells lysed in the aggregated state nucleate the assembly of only a few microtubules. We conclude that it is the activity of the CA that basically regulates the expression of microtubules. This regulation is achieved through a variation in the capacity to initiate microtubule assembly. Increase or decrease in the amount of dense material, as readily observed in the cell system studied here, seems to be a morphologic expression of such a physiologic function.

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